When do babies return to their birth weight?

We're talking about infant weight loss today! (The birthing person may also have questions about their own weight loss - that's a topic for another day.)

Especially among people breastfeeding (or chestfeeding) their babies, it's common to have concerns about the amount of weight your baby loses in the first few weeks. 

Some new research followed babies for one month after birth to see what the 'normal' patterns of weight gain are. First thing, there's no such thing as 'normal'! Every baby is different, every situation is different. Parents and birth workers have known this for well, millennia. But now the mainstream science community is catching up. 

So, lesson one from this research: your baby is unique. It's okay if they lose weight at a different rate than other babies. Trust yourself as their parent, the ones who know your baby best. 

Common Patterns for Infant Weight Loss

Almost 150,000 infants were included in this study. Let's look at what happened with their weights:

  • 10 days postpartum: 50% of newborns weighed the same or more than their birth weight
  • 2 weeks postpartum: Approximately 4 in 5 newborns weighed the same or more than their birth weight
  • 3 weeks postpartum: 92-95% on newborns weighed the same or more than their birth weight

 I can say this a different way: It's common for it to take over 3 weeks to return to birth weight! 

I know that 92-95% seems high. But given how big this study was, that means about 11,000 babies were not up to their birth weight at 3 weeks postpartum. That's a lot of babies. It's really quite common. 

Another thing this study noted was that it usually takes longer for babies born by Cesarean birth to regain their weight. If your baby was born by Cesarean (surgical birth), it will probably take a bit longer for them to gain weight, and that's normal too. 


If you have any concerns, bring them up with your care provider when you see them. In Ontario, health units often have free breastfeeding clinic where (even if you're not currently breastfeeding) you can weigh your baby. Then you don't have to wait until your next appointment to find out what their weight is. 

In the GTA, you can go to free breastfeeding clinics here:

Most of them are walk-in, so you don't need an appointment. Call ahead to make sure they have a scale if that's what you're looking for. 

In summary:

Research shows that it's quite common for it to take a couple weeks for babies to return to their birth weight. You know your baby the best - trust your instincts as a parent. 


with love, 



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